L20b Front Cover Issues

[alexmillikan]

Yeah at first I thought it was broken off in there but it was just crud I was able to clean it out and put a pin in from the old cover thanks guys

[alexmillikan]

Alright guys got the engine done and have probably 1 hour on it and this has happened. The rocker arms seem to be eating the cam I have an isky L475 cam and ITM rocker arms any ideas? Running royal purple break in oil 

https://drive.google.com/open?id=1xOO9FazmwTxgcAMs-HKIo5JaI4SXlpEm

 

[datzenmike]

Check the clearance first.

 

Run with the valve cover off. Got good oil spray happening???

 

Do you have the correct lash pads and is the cam lobe landing on the rocker arm pad properly?

 

 

Get rid of the 'break in oil' and get something non synthetic and high in ZDDP which is an anti scuff additive. Most diesel oils have it in abundance. The cam doesn't need to be broken in, just drive it. That's a V8 thing.

[alexmillikan]

https://drive.google.com/open?id=1byq0YBlAUyKledgdgv6BptMailU7gldM

Mike, if you look at that picture I think the damage has already been done and the royal purple oil is non synthetic and the description says High in zinc but the container does not have the ZDDP rating and the isky grease that cam wth the cam was used initially. I had the machine shop assemble the head so I did not check the cam lobe landing alignment. I know the lash caps are correct they are the ones isky said we’re required for the cam. The retainers, springs, lash caps and cam are all new isky products. Also the clearances are good.

[datzenmike]

Turn the cam till the lobe is about to land on the rocker arm. It definitely must NOT touch down off the pad.

 

What about adequate oiling for the cam???

 

 

 

[alexmillikan]

Just shut up the shop for the night I will check that stuff tomorrow but I never thought of that the cam touching the part of the rocker arm not on the pad. It never seemed to get hung when turning it over by hand just after assembling and setting the timing but I’m sure it’s possible. If it does touch what would be the problem bad rockers or wrong size lash cap? Thanks Mike!

[datzenmike]

It's probably not that, but, it must be examined and eliminated.

 

Lack of lubrication could also be a possibility.

[Crashtd420]

1 hour ago, alexmillikan said:

https://drive.google.com/open?id=1byq0YBlAUyKledgdgv6BptMailU7gldM

Mike, if you look at that picture I think the damage has already been done and the royal purple oil is non synthetic and the description says High in zinc but the container does not have the ZDDP rating and the isky grease that cam wth the cam was used initially. I had the machine shop assemble the head so I did not check the cam lobe landing alignment. I know the lash caps are correct they are the ones isky said we’re required for the cam. The retainers, springs, lash caps and cam are all new isky products. Also the clearances are good.

Just to say I dont think it's the break in oil.... I just used that same oil during my break in procedure of my L16, its excellent for the flat tapet cam....

If you plan on running royal purple oil after make sure it's the HPS line they sell, high in zinc and phosphorus ... 

 

But about your problem, the lack of lubrication like Mike said seems possible, since you say all the tolerances are good and parts are correct....

was any machine work done to the head itself or did they just do the assembly?

[datzenmike]

Are all lobes showing wear?

 

You replaced the rockers.... are they reconditioned original rockers?

[Stoffregen Motorsports]

12 hours ago, alexmillikan said:

Just shut up the shop for the night I will check that stuff tomorrow but I never thought of that the cam touching the part of the rocker arm not on the pad. It never seemed to get hung when turning it over by hand just after assembling and setting the timing but I’m sure it’s possible. If it does touch what would be the problem bad rockers or wrong size lash cap? Thanks Mike!

It's called rocker geometry. The wipe pattern on the rocker arm needs to be checked when installing custom cam, different lash lads or new valves, I'm sure there's a how-to somewhere, but it can be done simply by marking the wear surface of the rocker with a sharpie, rotating the cam a couple times and checking the wipe pattern. It should not come off the wear cap, and if it does, it can wipe out a cam in no time.

 

If your geometry is good, then either the cam wasn't heat treated properly, or ...?

 

Like Mike said, it ain't a V8, and cam break in isn't usually a problem on Datsun L motors.

 

But yeah, you need a new cam.

[alexmillikan]

I did replace the rockers per the suggestion in the manual but the only ones I could find were ITM rockers as I mentioned in my previous post. I still have the originals. Also if you look at the picture folder I linked in my previous post there are some lobes  that  look fine and other that are really bad.

[alexmillikan]

And thank you stoffregen, the machine shop told me they checked the geometry but did not give exact detail if the check the wear pattern on the lash cap and rocker arm pad or just one or the other. And that is thing same thing my father said possible bad heat treat on the cam because I looked at it after having the engine running for about 15 minutes and it appeared to be good, I just looked at it again after driving it a couple of times adding up to about 1 hour of total operation and found this when I went in to check the clearances hot and they were good .10 and .12 I&E.

[datzenmike]

The cam is drilled for oil supply. It's messy, but running with the valve cover off you can see if there are lobes not throwing oil.

[alexmillikan]

Alright guys the oiling is good so I’m down to geometry/ crappy rocker arms I uploaded a lot more photos to the folder of the engine turning over quickly (without spark plugs) and it was oiling properly. I also uploaded a video turning it over by hand and pictures of the new rocker arms and the old ones to compare. I’m about to do the wipe pattern with a sharpie to check geometry

https://drive.google.com/open?id=1xOO9FazmwTxgcAMs-HKIo5JaI4SXlpEm

[datzenmike]

Img. 4302 on the right looks like the wipe pattern is awfully close to the edge of the pad.

 

 

Are the rockers all the same length?

[alexmillikan]

8 minutes ago, datzenmike said:

Img. 4302 on the right looks like the wipe pattern is awfully close to the edge of the pad.

 

 

Are the rockers all the same length?

The rockers are the same but I just did some reading in How to Modify your Datsun OHC Engine "Different thickness lash pads allow adjustment of cam-lobe wipe pattern. Lash pads can be trimmed to exact size by using a lathe with a collet to hold the lash pads." If you look closely the Isky lash pads are completly flat on the bottom different than the stock ones so I believe my lash caps need to be trimmed. It became obvious when I saw how much smaller the wear mark was on the new lash pads and rocker arm tips compared to the old one and this meant the wear pattern was longer on the cam lobe side meaning the cam contacted the edges of the pad on almost every lobe. Lesson learned the hard way I guess, this is my first ever full engine rebuild and when buying the parts from Isky they made no mention of trimming the lash caps (I emailed them specifically asking what I needed) and my machinist ensured me the head was ready to go but it is clear now, he did not check the wear pattern. I will contact Isky Tuesday and see if the cam can be re ground and I will get some layout dye and check the wear patterns myself this time and get a friend of mine who has a lathe to take small amounts of material off the lash pads until we get the pattern right and I guess reuse the old rocker arms. Also with pulling the cam the rebuild manual tells you to pull it out the front but is it acceptable to take off the cam towers instead? Another question how do i measure to see if all of the valve stems are the same height? since I guess that could be an issue too.

[Rays74]

Tough to see on my phone but looks like that video shows #3 exh lobe nearly running off the end of the pad

[alexmillikan]

32 minutes ago, datzenmike said:

Img. 4302 on the right looks like the wipe pattern is awfully close to the edge of the pad.

 

 

Are the rockers all the same length?

To clarify on rocker arm length the new ones are the all the same length but they are shorter than the originals. I uploaded a couple more photos to the same folder, old rockers are about 3.080 new ones are 3.050 long

[datzenmike]

 

 

Flat or concave really won't matter unless they are measured wrong. The real thickness is from the center indented part to the top where the wear pattern is showing.  That thickness determines where the wipe pattern is centered on the rocker pad.

[alexmillikan]

Yeah I see, so have you ever heard of anyone milling a flat one to the right size for an isky cam or would you just try and get a stock one that is the correct thickness? and you can tell the wear pattern was way off y how narrow it is on the black lash cap

 

 

[datzenmike]

Well first you need to see exactly where the wipe pattern is before cutting anything. A thicker pad moves the wipe towards the valve spring, shorter moves it away.

 

Then there is the shorter rocker arms which presumably moves the pad away from the spring.

[Crashtd420]

"Also with pulling the cam the rebuild manual tells you to pull it out the front but is it acceptable to take off the cam towers instead?" Quoting alex

 

Seems like your on the right track, but do your self a favor and dont remove the cam towers... they need to stay in line perfectly.... 

 

 

 

[datzenmike]

you're

 

 

I would avoid taking the cam towers off at any cost.

 

 

1/ The cam tower bolts only take just over 10 ft lbs and the aluminum head threads are easily stripped.

2/ Getting the cam back in just right without any tight spots might be a problem. Certainly tighten (carefully) to the correct torque with the cam in place to help. Then spin by hand to be sure it won't bind.

[Rays74]

The cam towers can be pulled, it's not black magik and no harm has ever come to the engines I've rebuilt as long as you use the correct sequence upon reinstallation.

Install the towers with the cam in them finger tight (use plenty of asembly lube, grease whatever....I use Lucas cause I have it in the shop)......now without the rockers in place snug the towers down and keep spinning the cam every chance you get (place the cam sprocket on finger tight to help here), if or when you find the cam binding at all loosen the last tower you snugged and wiggle it a bit and try again. Now you may find the cam binding and loosening as you turn it that would indicate it has a slight bend or warp...... better to replace it at that point. I normally save the old towers and bit from heads that are being recycled so I can have a selection to pick through if I find I have a warped cam or bad tower (not often).

Here's a short videdo of me assembling a stock L18 and focusing on the cam and how smooth it needs to be.

Good luck,

-- Ray

https://www.youtube.com/watch?v=7n-xukHMwQA&t=3s

[Stoffregen Motorsports]

I didn't read all the new replies, but I feel we need to clarify something. You're not checking the wipe pattern on the lash pad, but on the wipe area of the rocker arm, where it meets the cam.